Substance abuse among adolescents is one of the most critical problems facing mental health, academic, and other professionals dealing with this age-group today. While the traditional adult literature has long presumed underlying psychopathology, including depression, to be etiologically significant in the development of substance abuse, and numerous reports exist documenting a large overlap between depression and drug-abuse or dependence in adults, studies examining this phenomenon in adolescent, or younger, populations are largely non-existent. The relationship between substance abuse and depression is important because of both the etiological role that one disorder may play in the development of the other and the fact that treatment outcome in substance-abusing individuals has been found to be deleteriously affected by the presence of co-existing affective illness, and vice versa. The proposed study will examine the socio-behavioral correlates of substance abuse in a clinically depressed adolescent sample in order to enhance current knowledge about the development and phenomenology of substance abuse in this group and provide an objective foundation for the development of prevention and treatment programs addressing the specific needs of this high-risk, dual-diagnosis population. Two groups of adolescents meeting DSM-IIIR criteria for major depressive disorder, one with a concurrent diagnosis of substance use disorder (Depression+SUD) and the other not meeting criteria for substance use disorder (Depression only), will be compared on measures of psychiatric status, interpersonal cognitive problem- solving (ICPS) abilities, and other familial, peer, and academic factors putatively related to the presence of substance abuse in this age range. Deficits in ICPS skills have been found in both young-adult heroin addicts and other psychiatrically-disturbed adolescent populations, and perhaps more importantly, have been shown to be amenable to various remediation efforts. It is predicted that the Depression+SUD group will exhibit a differential pattern of depressive symptomatology, a higher rate of additional lifetime psychiatric disorders, poorer ICPS abilities, and higher levels of parental and peer acceptance of, and actual, psychoactive substance use than the Depression only group. Moreover, the Depression+SUD group is also expected to be rated by teachers as showing lower levels of academic motivation and achievement than their non-drug abusing counterparts.